/*
 * Copyright (c) 2010, 2019 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package jakarta.ws.rs.ext;

import java.io.InputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

import jakarta.ws.rs.core.MediaType;
import jakarta.ws.rs.core.MultivaluedMap;

/**
 * Contract for a provider that supports the conversion of a stream to a Java type.
 *
 * A {@code MessageBodyReader} implementation may be annotated with {@link jakarta.ws.rs.Consumes} to restrict the media
 * types for which it will be considered suitable. The {@code MessageBodyReader} pipeline is executed if the matching
 * resource method declares an entity parameter or uses at least one {@link jakarta.ws.rs.FormParam}.
 * <p>
 * Providers implementing {@code MessageBodyReader} contract must be either programmatically registered in a JAX-RS
 * runtime or must be annotated with {@link jakarta.ws.rs.ext.Provider &#64;Provider} annotation to be automatically
 * discovered by the JAX-RS runtime during a provider scanning phase.
 * </p>
 *
 * @param <T> Java type supported by the provider
 * @author Paul Sandoz
 * @author Marc Hadley
 * @see Provider
 * @see jakarta.ws.rs.Consumes
 * @since 1.0
 */
public interface MessageBodyReader<T> {

    /**
     * Ascertain if the MessageBodyReader can produce an instance of a particular type. The {@code type} parameter gives the
     * class of the instance that should be produced, the {@code genericType} parameter gives the
     * {@link java.lang.reflect.Type java.lang.reflect.Type} of the instance that should be produced. E.g. if the instance
     * to be produced is {@code List<String>}, the {@code type} parameter will be {@code java.util.List} and the
     * {@code genericType} parameter will be {@link java.lang.reflect.ParameterizedType
     * java.lang.reflect.ParameterizedType}.
     *
     * @param type the class of instance to be produced.
     * @param genericType the type of instance to be produced. E.g. if the message body is to be converted into a method
     * parameter, this will be the formal type of the method parameter as returned by
     * {@code Method.getGenericParameterTypes}.
     * @param annotations an array of the annotations on the declaration of the artifact that will be initialized with the
     * produced instance. E.g. if the message body is to be converted into a method parameter, this will be the annotations
     * on that parameter returned by {@code Method.getParameterAnnotations}.
     * @param mediaType the media type of the HTTP entity, if one is not specified in the request then
     * {@code application/octet-stream} is used.
     * @return {@code true} if the type is supported, otherwise {@code false}.
     */
    public boolean isReadable(Class<?> type, Type genericType,
            Annotation[] annotations, MediaType mediaType);

    /**
     * Read a type from the {@link InputStream}.
     * <p>
     * In case the entity input stream is empty, the reader is expected to either return a Java representation of a
     * zero-length entity or throw a {@link jakarta.ws.rs.core.NoContentException} in case no zero-length entity
     * representation is defined for the supported Java type. A {@code NoContentException}, if thrown by a message body
     * reader while reading a server request entity, is automatically translated by JAX-RS server runtime into a
     * {@link jakarta.ws.rs.BadRequestException} wrapping the original {@code NoContentException} and rethrown for a standard
     * processing by the registered {@link jakarta.ws.rs.ext.ExceptionMapper exception mappers}.
     * </p>
     *
     * @param type the type that is to be read from the entity stream.
     * @param genericType the type of instance to be produced. E.g. if the message body is to be converted into a method
     * parameter, this will be the formal type of the method parameter as returned by
     * {@code Method.getGenericParameterTypes}.
     * @param annotations an array of the annotations on the declaration of the artifact that will be initialized with the
     * produced instance. E.g. if the message body is to be converted into a method parameter, this will be the annotations
     * on that parameter returned by {@code Method.getParameterAnnotations}.
     * @param mediaType the media type of the HTTP entity.
     * @param httpHeaders the read-only HTTP headers associated with HTTP entity.
     * @param entityStream the {@link InputStream} of the HTTP entity. The caller is responsible for ensuring that the input
     * stream ends when the entity has been consumed. The implementation should not close the input stream.
     * @return the type that was read from the stream. In case the entity input stream is empty, the reader is expected to
     * either return an instance representing a zero-length entity or throw a {@link jakarta.ws.rs.core.NoContentException} in
     * case no zero-length entity representation is defined for the supported Java type.
     * @throws java.io.IOException if an IO error arises. In case the entity input stream is empty and the reader is not
     * able to produce a Java representation for a zero-length entity, {@code NoContentException} is expected to be thrown.
     * @throws jakarta.ws.rs.WebApplicationException if a specific HTTP error response needs to be produced. Only effective if
     * thrown prior to the response being committed.
     */
    public T readFrom(Class<T> type, Type genericType,
            Annotation[] annotations, MediaType mediaType,
            MultivaluedMap<String, String> httpHeaders,
            InputStream entityStream) throws java.io.IOException, jakarta.ws.rs.WebApplicationException;
}
